MX2010012051A

MX2010012051A - Hydroxyl-functionalised poylurethane hot melt prepolymer.

Info

Publication number: MX2010012051A
Application number: MX2010012051A
Authority: MX
Inventors: Uwe Schuemann; Kirstin Weiland
Original assignee: Tesa Se
Priority date: 2008-05-13
Filing date: 2009-05-12
Publication date: 2010-12-01
Also published as: MX2009004762A; EP2119735A1; TWI439479B; ES2388048T3; JP2011521040A; PL2119735T3; TWI487722B; CN101638467A; US8653221B2; KR101660819B1; US20090286950A1; CA2723916A1; TW201000506A; US20110237760A1; WO2009138402A1; CN102089343A; KR20090118855A; TW201002749A; US8580909B2; CN101638467B

Abstract

The invention relates to hydroxyl-functionalised polyurethane hot melt prepolymers comprising the chemical reaction product of isocyanate-reactive starting materials with at least one isocyanate-containing starting material. Said prepolymers are characterised in that the isocyanate-reactive starting materials of the hydroxyl-functionalised polyurethane hot melt prepolymers have a polypropylene glycol with a functionality higher than two and a number-average molar mass higher than or equal to 3,000 g/mol, a polypropylene glycol with a functionality less than or equal to two and a number-average molar mass less than or equal to 1,000 g/mol, and a chain lengthener with a functionality less than or equal to 500 g/mol, and the isocyanate-containing starting material of the hydroxyl-functionalised polyurethane hot melt prepolymer has an aliphatic or alicyclic diisocyanate.

Description

PRE-POLYMER THERMOFUNDED POLYURETHANE FUNCTIONALIZED WITH HYDROXYL Field of the Invention The present invention relates to a hydroxyl functionalized polyurethane prepolymer that is solid at room temperature, is meltable, is soluble in numerous solvents, comprises long chain branching points, and has viscoelastic properties suitable for pressure sensitive adhesive applications , and also to its use.

Background of the Invention A characteristic of substances having suitable viscoelastic properties for pressure sensitive adhesive applications is that under mechanical deformation, they not only exhibit viscous flow but also develop elastic resistance forces. These two processes, in terms of their respective fraction, are in a particular proportion one to another, which is dependent not only on the exact composition, structure, and degree of cross-linking of the substance under consideration, but also on the index and duration of deformation, and in temperature.

The viscous flow of the component is necessary in order to obtain adhesion. Only viscous fractions, caused by macromolecules that have mobility Ref. : 215168 relatively high, they allow good surface tension and good flow on the substrate where the union occurs. A high viscous flow component results in a high inherent tack (also referred to as pressure sensitive adhesiveness) and therefore often also at a high bond strength. Vitreous or crystalline solidified polymers of highly crosslinked systems do not have inherent tackiness, generally speaking, due to a lack of dispersible components.

The elastic resistance forces of the component are necessary to obtain cohesion. They are caused, for example, by very long chain macromolecules with a high degree of interlacing, and also by physically or chemically crosslinked macromolecules,. and allows the transmission of the forces that act in an adhesive bond. Elastic resistive forces mean that an adhesive bond is able to adequately withstand, over a relatively long period of time, a long-term load that is acting on it, in the form, for example, of a sustained shear load.

For a more exact description and quantification of the degree of elastic and viscous components, and also of the proportion of the components one to another, it is possible to use the parameters - determinable by means of Dynamic Mechanical Analysis (DMA) - of the storage module (G '), module of loss (G ''), and also the proportion G '' / G ', which is identified as a loss factor so d (tan delta). G 'is a measure of the elastic component, G "a measure of the viscous component, of a substance. Both parameters are dependent on the frequency of deformation and the temperature.

The parameters can be determined by means of a rheometer. The material under analysis, in a plate / plate arrangement, for example, is subjected to an oscillating sinusoidal shearing stress. In the case of the instruments controlled by the shear stress, the deformation is measured as a function of time, and the time lapse of this deformation related to the introduction of the shear stress is measured. This time lapse is identified as phase angle d.

The storage modulus G 'is defined as follows: G' = T / Y »COS (5) (t = shear stress,? Deformation, d = phase angle = phase shift between the vector of the shear stress and the deformation vector). The definition of the loss modulus G '' = = i / Y «sin (5) (t _. = Shear stress,? = Deformation, d = phase angle = phase shift between the vector of the shear stress and the deformation vector).

A substance is generally considered appropriate for pressure sensitive adhesive applications (PSA, for its acronyms in terms of their viscoelastic properties when at room temperature in the frequency range from 10 ° to 101 rad / sec, ideally in the frequency range from 10"1 to 102 rad / sec, G 'is located in the interval from 103 to 106 Pa and when G "is also located in this interval. Within this range, which in a matrix diagram of G 'and G' '(G' plotted as a function of G '') can also be called the viscoelastic window for PSA applications, or as the PSA window, according to viscoelastic criteria, there are, in turn, different sectors and quadrants that most closely characterize the properties of pressure sensitive adhesive that will be expected from the associated substances. Substances with high G "and low G 'within this window, for example, are generally notable for high bond strength and low shear stress, while substances with a high G" and high G' are notable for high bond strength and high shear stress.

Generally speaking, the results with reference to the relationships between rheology and pressure sensitive adhesiveness are in the prior art and are described, for example, in "Satas, Handbook of Pressure Sensitive Adhesive Technology, Third Edition, (1999), pp. 153 -203".

. One of many alternative possibilities to characterize The viscoelastic properties of a substance is to determine the tensile deformation properties and the relaxation behavior in a tensile strain test. In the tensile strain test, the determined parameters include tensile strength and associated deformation. Relaxation behavior can also be. determined in a tensile strain test. This is done by measuring the effort at the moment that a defined deformation is achieved. The stress is defined as the tensile force in the sample body, relative to the initial transversely sectioned area within the measurement length. This deformation is also maintained. After a certain time, the effort is determined again. The percentage decrease in effort is relaxation.

Considering an adhesive tape or other kind of self-adhesive article, the viscoelastic properties suitable for PSA applications are initially important for the PSA layer of the self-adhesive article. For other layers of an adhesive tape also, however, the viscoelastic properties suitable for PSA applications may be important. This is because the PSA properties of an adhesive tape are influenced not only by the viscoelastic properties of the PSA layer, but also by the corresponding properties of the other layers, and also the thickness of the layers. The beginning of the window Viscoelastic for PSA applications is widespread, that is, through all the layers of an adhesive tape. Therefore a layer having suitable viscoelastic properties for PSA applications can often also be advantageously used as a carrier layer. Even for functional layers of an adhesive tape, the viscoelastic properties suitable for PSA applications can be advantageous. The functional layers can be, for example, primer layers or layers having particular optical, electrical or heat conducting properties, to give some examples.

As regards the production of self-adhesive articles in a continuous coating operation, there are various known technologies. Fundamentally, a distinction can be made between solvent-based and solvent-free technologies.

In solvent-based systems, the pressure-sensitive adhesive polymer or pressure-sensitive adhesive mixture is usually present in the non-crosslinked solution before coating. Shortly before coating on a carrier or auxiliary carrier, a chemical crosslinker can be mixed. After the coating has occurred, and after the evaporation of the solvent, the polymer or mixture of substances of pressure sensitive adhesive is present in the form of a film or layer similar to film in the carrier or auxiliary carrier, and can be rolled, regardless of whether the crosslinking process has already been completed or not. Generally speaking, the reticulation has none. marked influence on the solid character of the polymer or mixture of substances of pressure-sensitive adhesive, this solid character which is the basic prerequisite for roll-up.

Solvent-based technologies have the fundamental disadvantage that they are not suitable for producing thick layers, especially not when the coating is to occur at an economically acceptable rate. Even at layer thicknesses above about 100 to 150 μp ?, the swelling visible as a result of solvent evaporation is increased, and therefore there are different quality detractions, which means that the layer can not be considered anymore for use on an adhesive tape. In the context of the production of thinner layers also, the speed of coating is considerably limited by the need to evaporate the solvent. In addition, solvent-based coating operations result in considerable operational costs as a result of the need for solvent recovery or incineration.

Systems without solvent can be subdivided into reactive systems, which are liquid, syrup-like, or paste-like even without solvent at room temperature environment, and in hot melt systems, where the polymer or mixture of adhesive substances are solid at room temperature and, when heat is applied, they can be melted.

Typical examples of reactive systems that are liquid, syrup-like or paste-like at room temperature are well-known two-component polyurethanes, epoxides or silicones. Reagent systems of this kind can be used to produce both thin and thick layers, this is a great advantage over solvent based systems.

In relation, however, to the production of adhesive tape, reactive systems that are liquid, syrup-like or similar to paste at room temperature have the disadvantage that in this state they can not be rolled, or at least not with layer thickness constant, especially not when layer thicknesses are high. With constant layer thicknesses it is possible to roll only polymer films that are solid. The solidification of reactive systems without solvent that are liquid at room temperature is linked to the progress of a chemical reaction that generally begins after the components have been mixed. The progress of the reaction requires a certain time. Only when the film has solidified as a result of a sufficiently high degree of conversion in the chemical reaction in question is it possible that the coated film on a carrier or auxiliary carrier is wound. Therefore, the coating speed for such systems is unlimited.

The PSAs based on polyurethane described in EP 1 469 024 A2, in EP 1 469 055 Bl, in EP 1 849 811 Al or in WO 2008/009542 fall within this category of reactive systems. As a film and / or PSA layer, as part of an adhesive tape, therefore, they can only be produced with a coating speed which is limited and therefore, as a rule, not very economical.

The self-adhesive polyurethane tape carriers described in EP 0 801 121 Bl and EP O 894 841 Bl also, like the PSAs set forth above, have the disadvantage that they are produced during the coating of the liquid or paste-like components. Here also, therefore, it is necessary to wait for the progress of the reaction until these carriers can be wound up, and this limits the speed of coating and therefore the economy of production. The same disadvantage applies with respect to the substances produced by the process described in EP 1 095 993 Bl for the continuous production of self-adhesive articles of two-component polyurethanes.

Adhesive tapes or adhesive tape layers based on syrup-like components are described for example in EP 0 259 094 Bl or in EP 0 305161 Bl, where the accumulation or polymer crosslinking is achieved through photopolymerization.

These reactive systems also have the disadvantage that in their syrup-like state they can not be rolled, or at least not with constant layer thickness. Here again, roll-up is linked to the progress of the reaction, which requires some time. Therefore these systems are also limited in terms of coating speed.

Liquid, syrup-like or paste-like reactive systems whose accumulation of polymer and whose crosslinking is initiated externally, such as by UV or EBC radiation, have the additional disadvantage, in general, that polymer accumulation with consistently homogeneous properties occurs only when the radiation, uniformly, reaches all the molecules involved in the polymer accumulation, through the full thickness of the film. Particularly at high layer thicknesses or with systems that are filled with fillers, this is not the case, and such that such films then have a cross-linked polymer frame inhomogeneously.

Compared with liquid, syrup-like or paste-like reactive systems, hot-melt systems have the advantage that they can be used to obtain high coating speeds, especially in the context of its process in extrusion operations. In extrusion operations, the meltable polymers which at room temperature are solid (thermofused), and in which the state, at higher temperatures, they are shaped to a film, and coated, generally, on a carrier or auxiliary carrier. After cooling and therefore solidification has occurred, rolling can be performed immediately. Rollability is not linked to the progress of a chemical reaction. The operation of cooling a film generally only takes comparatively little time. As with liquid, syrup-like or paste-like reagent systems, hot melt systems can also be used to produce layers without any fundamental limitation in thickness. In the adhesive tape area, there are mainly styrene block copolymer PSAs, described for example in DE 100 03 318 A1 or DE 102 52 088 Al, which are coated in this manner.

For hot-melt systems, however, in general, due to high processing temperatures and the associated restriction for thermal crosslinking processes, the problem arises, when the crosslinking layers use actinic radiation, the depth of restricted penetration of thickness and thickness-dependent penetration intensity of the radiation means that the Proper homogenous crosslinking through the layer is not possible, especially for thick layers.

Thermoplastic polyurethanes can also be processed by hot melt operations. DE 20 59 570 A describes, for example, a continuous single-pass production process for a non-porous thermoplastic polyurethane.

The preparation of thermoplastically processable polyurethanes of an OH-terminated linear prepolymer initially prepared as an intermediate is described in DE10 2005 039 933 A, for example. DE 22 48 382 C2 also describes the preparation of thermoplastic polyurethanes of the OH-terminated prepolymers in a multi-stage operation. These specifications do not use any polyol that has a functionality higher than two. No indication of the appropriate viscoelastic properties for PSA applications is given in the part of the polyurethanes that can be prepared by the teachings of these specifications. In US 2007/0049719 A1 also, hydroxyl terminated polyurethane prepolymers are disclosed. There again, the prepolymers are exclusively linear, constructed from purely dysfunctional starting materials without branching sites. There are also no indications of viscoelastic properties suitable for PSA applications.

Hydroxyl-terminated polyurethane prepolymers they are further described in US 2007/0129456 Al. These polymers serve to produce synthetic leather, and are liquid or semi-solid at room temperature. They comprise crystalline polyether polyol and crystalline polyester polyol. No indications of appropriate viscoelastic properties are given for PSA applications. Nor is there any indication given of these prepolymers having a sufficiently solid character to be rolled up in the form of a roll of adhesive tape.

Thermoforming coating operations based on thermoplastic or thermoplastically processable polymers have the advantages that high coating speed and the ability to produce thick layers can be achieved, but they lead to polymer films that are not crosslinked or at least not crosslinked suitably, with the consequence that these films are unsuitable for use as layers of adhesive tape, for which there must be a high long-term strength, particularly at elevated temperatures.

The extrusion of polyurethane elastomers using triols which can lead to a crosslinked character in the elastomers is known from DE 19 64 834 A and DE 23 02 564 C3, for example. These specifications, however, describe the reaction of the liquid starting materials, with the additional disadvantage that, before such elastomers are rolled up, it is necessary to await the solidification which is dependent on the progress of the reaction. No indication is given of the viscoelastic properties appropriate for PSA applications with respect to the products produced by the processes described in these specifications. In the processes described in these specifications, on the other hand, only isocyanate-terminated prepolymers are used, instead of hydroxyl-terminated prepolymers. The molecular weight of the triols used in these specifications has an upper limit of 500.

EP 135 111 81 describes the preparation of polyurethanes which are branched, but are thermoplastically processable and therefore not crosslinked, in a multi-step process. Proposed as a first intermediate A is an OH-terminated prepolymer constructed of substantially linear polyhydroxyl compounds of relatively high molecular weight. The lower limit on the molecular weight of the polyhydroxyl compounds is 550. There are no indications of suitable viscoelastic properties for PSA applications, or of hot-melt properties in the OH-terminated prepolymer portion.

JP 2006/182795 discloses a hydroxyl functionalized polyurethane prepolymer formed of a polyether polyol mixture, consisting of a polyether diol and a polyether triol, and polyisocyanate. The average functionality of the polyol mixture is 2.2 to 3.4. In addition, the reaction of this prepolymer is described with a polyfunctional isocyanate to form an adhesive film. The polyurethane prepolymer functionalized with hydroxyl in JP 2006/182795, however, is not a hot melt. In JP 2006/182795, the molecular weight of the diols is given a lower limit of 700. No indication of the appropriate viscoelastic properties is given for PSA applications.

Hot melt coating operations leading to crosslinked polymer films are known from DE 10 2004 044 086 Al, for example. Disclosed therein is a method for producing an adhesive tape based on an acrylate hot melt PSA, to which, in its molten state in an extruder, a thermal crosslinker is added.

One difficulty in the method described therein is the need first to polymerize the hot-melt acrylate PSA in a solvent and then extract this solvent again by means of a concentrating extruder. A further disadvantage is the relatively high molar mass of polyacrylate (Mw average weight: 300 000 to 1 500 000 g / mol). High molar masses dictate high processing temperatures and therefore high operating costs, and in extrusion operations, in addition, may result in unequal polymer properties in longitudinal and transverse directions.

Brief Description of the Invention It is an object of the invention to provide a substance or composition of matter that avoids or at least attenuates the disadvantages of prior art.

With particular advantage, a substance or composition of this kind must meet one, and advantageously two or more, preferably all, of the following criteria: The substance and the composition will have appropriate viscoelastic properties for pressure sensitive adhesive applications, ie, both the storage modulus G 'and the loss modulus G "of the substance or composition will be in the range from 103 Pa to 106. Pa, as determined at room temperature in the deformation frequency range from 10 ° to 101 rad / sec, preferably in the strain frequency range from 10"to 102 rad / sec, by Dynamic Mechanical Analysis (DMA) using . a rheometer controlled by shear stress in a plate / plate arrangement. The substance and composition will be chemically crosslinkable and in particular, even after crosslinking, they will have appropriate viscoelastic properties for PSA applications, according to the criteria set forth above. In terms of its viscoelastic properties, the substance and composition will allow a wide spectrum of variation possibilities, thus allowing a broad spectrum of PSA properties to be established. The substance and composition, after cross-linking, will be suitable for use as carrier layers, PSA layers or as functional layers in adhesive tapes or other self-adhesive articles.

The substance and composition will be thermofused, which means that they will be solid at room temperature and meltable by the supply of heat.

The substance and composition may optionally be coated and crosslinked in a continuous coating and crosslinking operation, such as in an extrusion process, for example, or in a batch process.

The substance and composition will be so that they will not have the disadvantages of prior art, or at least not to the same degree. In particular, the substance composition will be favorable for the preparation and processing without solvent. Where necessary, however, they will also be able to be prepared and processed in solvents. The crosslinked polymer films produced from the substance or composition in an extrusion operation will have properties that are equal in longitudinal and transverse directions.

This object is achieved by means of a thermofused polyurethane-functionalized hydroxyl prepolymer according to that registered in the main claim. The dependent claims provide advantageous developments of the prepolymer, the process for preparing it, and its possibilities for use.

The present invention relates more particularly to a hydroxyl functionalized polyurethane prepolymer which is solid at room temperature, is meltable, is soluble in numerous solvents, comprises long chain branching sites, and has viscoelastic properties suitable for PSA applications. Through the reaction with at least dysfunctional polyisocyanates and coating during the reaction phase, it is possible to produce from this prepolymer a chemically cross-linked polyurethane film having viscoelastic properties which are suitable for PSA applications, and which therefore can find use as a layer of PSA, the carrier layer or functional layer in adhesive tapes or other self-adhesive articles. The reaction with at least dysfunctional polyisocyanates can optionally occur in the solution or in the melt. The crosslinking and coating operation may optionally occur continuously, such as in an extrusion process, for example, or discontinuously.

The main claim relates to a thermofused polyurethane prepolymer functionalized with hydroxyl which is or comprises the chemical reaction product of isocyanate-reactive starting materials with at least one isocyanate-containing starting material, characterized in that the starting materials reagents with isocyanate of the hydroxyl-functionalized polyurethane hot melt prepolymer are or comprise at least one polypropylene glycol having a functionality of more than two and an average molar number greater than or equal to 3000 g / mol (referred to below as "polypropylene glycol PI") ), at least one polypropylene glycol having a functionality less than or equal to two and a number of average molar mass less than or equal to 1000 g / mol (referred to below as "polypropylene glycol PII"), and a chain extender having a functionality less than or equal to two and an average molar mass number less than 500 g / mol (referred to below as "KI chain extender"), and in which the isocyanate starting material of the hydroxyl functionalized polyurethane hot melt prepolymer is or comprises an aliphatic or alicyclic diisocyanate.

The hydroxyl-functionalized polyurethane-based prepolymer, therefore, is characterized in particular by the fact that it can be obtained by the reaction of at least three isocyanate-reactive components and at least one isocyanate-containing component. In an advantageous embodiment of the invention, the average molar mass number of the polypropylene glycol PII is at least twice as large, or greater, than that of the chain extender KI, and with particular preference is at least three times as large. or older .

Polymers or prepolymers which have the ability to be meltable and therefore be thermoplastically processable are identified in this specification, as is usual in the jargon of the person skilled in the art, as hot melts.

Detailed description of the invention A polyurethane hot melt prepolymer in this specification means a reaction production, especially a meltable reaction product, which is obtained by the chemical reaction of a mixture comprising two or more polyols with one or more polyisocyanates, and which at room temperature, it has a dimensional stability and robustness so that a compounding operation is possible at room temperature in known mixing assemblies (and also, in particular, a shaping operation or similar processing steps) without the addition of solvents, diluents or other adjuvants that lower the viscosity. Examples of known mixing assemblies include formulators, internal mixers, extruders, planetary roller extruders, planetary mixers, butterfly mixers or solvents. The processability of a meltable reaction product for the purposes of this specification is possible only when the meltable reaction product is heated, this is possible for the heat to be supplied from the outside, by heating, or is generated by shearing. Typical processing temperatures for meltable reaction products for the purposes of this specification are in the range of 70 ° to 160 ° C, and are at least 40 ° C. The ambient temperature for the purposes of this specification is in the temperature range from 20 ° C to 25 ° C, ideally 23 ° C. ' A meltable reaction product for the purposes of this specification has a complex viscosity, measured with a rheometer in an oscillation experiment with a sinusoidal oscillation shear stress in a plate / plate arrangement, at a temperature of 23 ° C and a frequency of oscillation of 10 rad / s, of at least 8000 Pas, preferably at least 10000 Pas. At 70 ° C and a frequency of 10 rad / s, the complex viscosity is at least 100 Pas, preferably at least 200 Pas.

The complex viscosity? * Is defined as follows: ? * = G * / co (G * = complex shear modulus,? = Angular frequency).

The additional definitions are as follows: G * = ^ (') 2 + (G ") 2 (G '' = viscosity module (loss modulus), G '= modulus of elasticity (storage modulus)).

G '' = t / ysen (d) (t = shear stress,? Deformation, d = phase angle = phase shift between the vector of the shear stress and the deformation vector) G '= T / Y «COS (5) (t = shear stress,? Deformation, d = phase angle = phase shift between the shear stress vector and the deformation vector). ? = 2? ·? (f = frequency).

It has been found surprisingly that the viscoelastic properties appropriate for PSA applications, in combination with the properties of hot melt and crosslinking through the additional reaction of the prepolymer. hydroxyl-functionalized polyurethane hot melt with one or more polyisocyanates, are achieved in particular when the hydroxyl-functionalized polyurethane pre-polymer comprises branching sites and when the substances from which the branching sites begin are or comprise isocyanate-reactive starting materials of the hydroxyl-functionalized polyurethane hot melt prepolymer which in turn are or comprise at least one polypropylene glycol having a functionality of more than two and an average molar mass number of greater than or equal to 3000 g / mol (polypropylene glycol PI) , at least one polypropylene glycol having a functionality less than or equal to two and a number of average molar mass less than or equal to 1000 g / mol (polypropylene glycol PII) and at least one chain extender having a functionality less than or equal to two and an average molar number less than or equal to 500 g / mol (chain extender KI), and when the isocyanate starting material of the prepolymer hydroxyl-functionalized polyurethane hot melt is or comprises an aliphatic or alicyclic diisocyanate. The branching sites also start with all the molecules with a functionality of three or more that participate in the chemical construction of the hydroxyl-functionalized polyurethane hot-melt prepolymer. The degree of branching is adjusted, in interaction with the length of the prepolymer chains produced, in order to ensure that this hydroxyl-functionalized polyurethane prepolymer is meltable, i.e., unless additional crosslinking substances are added. , do not form any reticulated structures. Only when the fraction of branching sites in the prepolymer exceeds a certain level, whose calculation or arithmetic evaluation is briefly described below, gelation is initiated - that is, the cross-linked structures are formed.

The proportion of the total number of isocyanate groups with respect to the total number of hydroxyl groups, referred for brevity below as a proportion of NCO / OH, of the starting materials involved in the molecular construction of the polyurethane hot melt prepolymer functionalized with hydroxyl is in particular less than 1.0, in order to achieve functionalization of the hydroxyl. In order to discard reticulated structures, the so-called gelling point must not be exceeded. The theoretical gelling point can be calculated using the gelation point equation of P.J. Flory. A formula derived from the Flory equation and used to estimate the gelation ratio of NCO / OH in polyurethane formation reactions of the diols and triols with diisocyanates in deficit works as follows: If the gelation ratio of NCO / OH is achieved or exceeded, it is likely that cross-linked structures are formed, and therefore gelation will begin. In practice, however, this is often not the case, since many of the commercially available diols or triols also include a fraction of monofunctional molecules - usually undefined. Therefore, the formula provides only an approximate indication of the proportion of NCO / OH in which the actual gelation point is achieved.

Diol OH in this formula refers to the total number of hydroxyl groups that participate in the formation reaction of the prepolymer and that originate from the dysfunctional polyols. Triol OH, is therefore the total number of hydroxyl groups participating in the formation reaction of the prepolymer and bound to the trifunctional polyols. Where, for example, exclusively the trifunctional polyols are reacted with diisocyanate to give a hydroxyl-functionalized prepolymer, the critical NCO / OH ratio is 0.5. If this NCO / OH ratio is exceeded, it is likely that the crosslinked structures will be formed, and therefore that gelation will occur, leading to prepolymers that can not melt.

To make sure that the hydroxyl functionalized polyurethane prepolymer is solid at room temperature, it is necessary to be careful that the crystalline melting point, the temperature of. glass transition or both are or are above room temperature or at least in the vicinity of room temperature. This can be done in a variety of ways by means of the selection and association of the. polyisocyanates and polyols that participate in the reaction to form the hot-melt polyurethane-functionalized prepolymer with hydroxyl. For example, crystalline polyols that are solid at room temperature can be used, or a high fraction of short chain polyols can be used, driving, after the reaction with the polyisocyanate, at a high fraction of hard segments within the structure of the prepolymer. The person skilled in the art, however, must assume that a hydroxyl functionalized polyurethane prepolymer does not have suitable viscoelastic properties for PSA applications as soon as the crystalline melting point, the vitreous transition temperature or possibly both are above. the ambient temperature or at least in the vicinity of the ambient temperature.

It has been surprisingly found that hot melt properties in combination with crosslinking and viscoelastic properties that are appropriate for PSA applications are achieved when the isocyanate-reactive starting materials of the hydroxyl-functionalized polyurethane pre-polymerized thermoplastic comprise at least one polypropylene glycol PII having a functionality less than or equal to two and an average molar number less than or equal to 1000 g / mol and at least one KI chain extender having a functionality less than or equal to two and a number of average molar mass less than or equal to 500 g / mol, when the isocyanate-containing starting material of the hydroxyl-functionalized polyurethane hot-melt prepolymer comprises an aliphatic or alicyclic diisocyanate, and when, in addition, the starting materials reactive with isocyanate of the hydroxyl-functionalized polyurethane prepolymer comprises a polypropylene glycol pl having a functionality greater than two and an average molar mass number greater than or equal to 3000 g / rriol.

The hot melt character can be advantageously achieved by providing the numerical fraction of the molecules involved in the molecular construction of the hydroxyl-functionalized polyurethane hot melt prepolymer and have a relative molar mass of less than or equal to 1000 g / mol which is at least 70%, preferably at least 80%. The numerical fraction always corresponds to the fraction of the quantity of substance.

The viscoelastic properties suitable for particularly typical "general purpose" PSA applications can be achieved, in combination with the properties of hot melt and crosslinking, when the numerical fraction of the hydroxyl groups that are introduced to form the hot-melt polyurethane prepolymer functionalized with hydroxyl and which originates from a polypropylene glycol having a functionality of more than two and a number of average molar mass greater than or equal to 3000 g / mol (polypropylene glycol PI) is at least 2.5%, preferably at least 5.0% and / or not more than 25.0%, preferably not more than 20.0%. . The viscoelastic properties appropriate for PSA applications. from "General purpose" particularly typical, can also advantageously be achieved, in combination with the properties of hot melt and crosslinking, when the number of average molar mass of the polypropylene glycol PI having a functionality greater than two is greater than or equal to 4500 g / mol , preferably greater than or equal to 5500 g / mol, the average molar mass number of the polypropylene glycol PII having a functionality less than or equal to two is less than or equal to 800 g / mol, preferably less than or equal to 600 g / mol, or when the average molar mass number of the chain extender KI has a functionality less than or equal to two is less than or equal to 400 g / mol, preferably less than or equal to 200 g / mol. A particularly preferred chain extender is 2-methyl-1,3-propanediol.

To achieve the appropriate viscoelastic properties for particularly typical "general purpose" PSA applications, it has emerged as being particularly favorable if the aliphatic or alicyclic diisocyanate is or comprises dicyclohexylmethane diisocyanate and / or isophorone diisocyanate.

In view of the use of the hydroxyl-functionalized polyurethane-based pre-polymer as a layer in an adhesive tape or in a self-adhesive article, it has been found that the particularly advantageous viscoelastic properties are suitable for PSA applications and that allow the development of custom adhesive tape layers, tailored to the variables, changing the requirement profiles, are achieved when the prepolymer chains are formed while possible, regardless of whether the hydroxyl-functionalized polyurethane pre-polymer is further reacted with polyisocyanates, and in particular, therefore, crosslinked. This is achieved by establishing the ratio of the total number of isocyanate groups to the total number of hydroxyl groups of the starting materials involved in the molecular construction of the hydroxyl-functionalized polyurethane hot-melt prepolymer is greater than or equal to 0.80 and less than or equal to 0.98, preferably between greater than or equal to 0.85 and less than or equal to 0.97, preferably between greater than or equal to 0.90 and less than or equal to 0.96. The average molar mass weight of the resulting prepolymers is then about 50,000 to 150,000 g / mol. This is a range that allows a smooth coating such as a hot melt, without producing distinct marked properties of the resulting film in longitudinal and transverse directions, such properties are detrimental to uses.

Particularly the viscoelastic properties suitable for PSA applications are achieved, also, when a fraction of the weight greater than or equal to 70% by weight of the polyols that participate in the formation of the thermofused hydropolylated polyurethane prepolymer are polyether polyols, preferably polypropylene glycols.

In view of the use of the hydroxyl-functionalized polyurethane-based polyurethane prepolymer as a layer in an adhesive tape or in a self-adhesive article, it is possible, after the reaction with polyisocyanate, to achieve an advantageous degree of crosslinking if, in advance, the numerical fraction of the molecules having a functionality of more than two and participating in the molecular construction of the hydroxyl-functionalized polyurethane hot-melt prepolymer is at least 0.5%, preferably at least 2.0%.

Generally speaking, polyurethane prepolymers are prior art in their preparation and are described in, for example, "Kunststoff-Handbuch, Polyurethane, ed .: Guenter Oertel, 3rd edition, 88-103, (1993)".

The isocyanate-reactive starting materials for preparing the prepolymer. Polyurethane hot melt fused with hydroxyl can be all known polyols such as, for example, polyether polyols, especially polyethylene glycols or polypropylene glycols, polyester polyols, polycarbonate polyols, polytetramethylene glycol ethers (polytetrahydrofurans), polybutadiene functionalized with hydrogenated and non-hydrogenated hydroxyl, hydrogenated and non-hydrogenated hydroxyl-functionalized polyisoprenes, hydroxyl-functionalized polyisobutylenes, hydroxyl-functionalized polyolefins or hydrogenated and non-hydrogenated hydroxyl-functionalized hydrocarbons. Preferred polyols are polypropylene glycols. As polypropylene glycols it is possible to use all commercial polyethers based on propylene oxide and a difunctional starting compound, in the case of the diols, and in a trifunctional starting compound, in the case of the triols. These include not only conventionally prepared polypropylene glycols, in this case, in general, with a basic catalyst, such as potassium hydroxide, for example, but also particularly pure polypropylene glycols which are prepared with catalysis of DMC (double metal cyanide) and whose preparation is described in, example, US 5,712,216, US 5,693,584, OR 99/56874, OR 99/51661, WO 99/59719, WO 99/64152, US 5,952,261, WO 99/64493, and WO 99/51657. A characteristic of polypropylene glycols catalysed WITH DMC is that the "nominal" or theoretical functionality of exactly 2 in the case of diols or exactly 3 in the case of triols is also really approximate. With conventionally prepared polypropylene glycols, functionality "true" is always somewhat lower than its theoretical counterpart, and this is particularly the case with polypropylene glycols having a relatively high molar mass. The reason is a secondary reordering reaction of propylene oxide to give the allyl alcohol. It is also possible, in addition, to use all polypropylene glycol diols and triols in which the ethylene oxide is also copolymerized, this is the case in many commercial polypropylene glycols, to achieve an increased reactivity with respect to the isocyanates.

Other isocyanate-reactive substances also, such as polyetheramines, for example, may be involved in the synthesis of hydroxyl-functionalized polyurethane hot-melt prepolymer.

Generally, for the purposes of this specification, isocyanate-reactive substances are all substances that contain active hydrogen. Active hydrogen is defined as hydrogen that is attached to nitrogen, oxygen or sulfur and reacts with methylmagnesium iodide in butyl ethers or other ethers in a reaction in which methane develops.

Chain extenders for the purposes of this specification are all isocyanate-reactive compounds having a functionality less than or equal to two and an average molar mass number less than or equal to 500 g / mole. In general these are difunctional compounds of low molar mass such as, for example, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1-butanediol, 2,3 -butanediol, propylene glycol, dipropylene glycol, 1,4-cyclohexanedimethanol, hydroquinone dihydroxyethyl ether, ethanolamine, N-phenyldiethanolamine ,. or m-phenylenediamine. The chain extender title also, however, encompasses the polyols described above, especially the polypropylene glycols, provided their functionality is less than or equal to two and their average molar mass number is less than or equal to 500 g / mol.

Crosslinkers can also be used. The crosslinkers are the isocyanate-reactive compounds of low molar mass having a functionality of more than two. Examples of crosslinkers are glycerol, trimethylolpropane, diethanolamine, triethanolamine and / or 1,2,4-butanetriol.

Isocyanate reactive substances, monofunctional, such as monooles, for example, can also be used. They serve as chain terminators and therefore can be used to control the chain length.

Isocyanate-containing starting materials contemplated for the preparation of hydroxyl-functionalized polyurethane hot-melt prepolymer include, for example, isophorone diisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tolylene diisocyanate, 4'-diphenylmethane diisocyanate or m-tetramethylxaryl diisocyanate, (TMXDI), mixtures of the indicated isocyanates, or isocyanates chemically derived therefrom, examples are dimerized, trimerized or polymerized types containing, groups for example, urea, uretdione or isocyanurate. An example of a dimerized type is uretdione HDI Desmodur N3400® from Bayer. An example of a trimerized type is HDI Desmodur N 3300® isocyanurate, also from Bayer. Examples of aliphatic and cycloaliphatic diisocyanates are isophorone diisocyanate, hexamethylene diisocyanate or 4,4'-dicyclohexylmethane diisocyanate. "Particularly preferred are isophorone diisocyanate and 4,4'-dicyclohexylmethane diisocyanate.

In order to accelerate the reaction of the isocyanate-reactive starting materials with at least one isocyanate-containing starting material, it is possible to use one or more catalysts known to the person skilled in the art, such as tertiary amines, organobismuth compounds or compounds of organotin, for example, to name a few. With great advantage it is possible to use catalysts comprising bismuth and carbon, preferably a bismuth carboxylate or a bismuth carboxylate derivative. The concentration of the catalysts is harmonized with the polyisocyanates and polyols used and also with the desired residence time in the mixing assembly and the temperature in the mixing assembly. Generally speaking, the concentration is between 0.01% by weight and 0.5% by weight of the chemically cross-linked polyurethane film to be prepared.

In a possible embodiment, the hydroxyl-functionalized polyurethane pre-polymerized thermoplastic comprises one or more additional formulation components such as, for example, fillers, microspheres, resins, especially adherent hydrocarbon resins, plasticizers, aging inhibitors (antioxidants), stabilizers. of light, UV absorbers, rheological additives, and other auxiliaries and adjuvants.

Fillers that may be used include reinforcement fillers, such as carbon black, for example, and fillers without reinforcement, such as barium sulfate or chalk, for example. Other examples are talc, mica, fumed silica, silicates, zinc oxide, solid glass microspheres, hollow glass microspheres and / or microspheres of plastics of all kinds. Mixtures of the indicated substances can also be used.

The use of antioxidants is advantageous, however, not obligatory.

Suitable antioxidants include, for example, sterically hindered phenols, hydroquinone derivatives, amines, organic sulfur compounds or organic phosphorus compounds. The light stabilizers and UV absorbers can also be optionally used. The light stabilizers used include, for example, the compounds described in Gaechter and Müller, Taschenbuch der Kunststoff-Additive, Munich 1979, in Kirk-Othmer (3rd) 23, 615 to 627, in Encycl. Polim. LCC Technol. 1.4, 125 to 148, and Ullmann (4th) 8, 21; 15, 529,676.

Examples of rheological additives that can optionally be added are fumed silicas, phyllosilicates (bentonites), high molecular weight polyamide powders or pulverized castor oil derivatives.

The additional use of plasticizers is also possible, but preferably it should be avoided because of its strong migration tendencies.

The hydroxyl-functionalized polyurethane prepolymer can be prepared batchwise (in this case, batchwise), such as in a heat-settable formulator, a planetary mixer or a solvent, or continuously, as for example in an extruder. or by means of a two-component mixer and a measuring system. The hydroxyl-functionalized polyurethane-based polyurethane prepolymer can also be prepared in steps, in which case combinations of mixing techniques are also possible. To ensure absence of bubbles, mixing occurs preferably under reduced pressure.

The invention is further provided for the further processing of the hot-melt polyurethane-functionalized prepolymer with hydroxyl, especially for the production of the polyurethane moldings and / or polyurethane layers.

The thermofused polyurethane prepolymer functionalized with hydroxyl of the invention can be used for the purpose - especially in a continuous process regime - which will be mixed in the melt (in particular, therefore, without solvent) with one or more at less difunctional polyisocyanates in a mixing assembly and therefore to be chemically reacted, in particular continuously, to finally give a molding or chemically crosslinked polyurethane film, in particular having suitable viscoelastic properties for PSA applications.

Continuous or continuous process regime means that, during mixing, the substances that will be mixed are supplied continuously and at a uniform rate to the mixing assembly, in other words they are introduced into the assembly, and the mixture in which the gradual chemical reaction to give the polymer progresses, it comes out continuously and at a uniform rate at another location of the mixing assembly.

In the mixing assembly, therefore, in the course of mixing, there is a process of continuous, uniform flow and / or transport process. The residence time of the substances in the mixing assembly from the introduction to the outlet in the form of a chemically reactive mixture (in particular, therefore, the reaction time of the hot-melt polyurethane prepolymer with the polyisocyanate or polyisocyanates before settling) preferably does not exceed 10 minutes and most preferably amounts from 2 seconds to 5 minutes.

The functionality of the polyisocyanates with which the hydroxyl-functionalized polyurethane-functionalized prepolymer of the invention is reacted, and the ratio of the total number of isocyanate groups to the total number of hydroxyl groups of the starting materials involved in the molecular construction of the polymer formed, as a result, through the continuously progressing chemical reaction, are preferably set up so that, after the complete reaction, the film is chemically crosslinked and therefore no longer meltable. As a general rule, an NCO / OH ratio between 1.0 and 1.1 is selected. An NCO / OH ratio greater than 1.0, that is, an excess of NCO, results in a polymer chain accumulation or crosslinking, by means of a virtually ubiquitous environmental moisture reaction. A NCO / OH ratio of less than 1.0 can be selected in particular when using polyisocyanates having a functionality of three or more. The appropriate polyisocyanates are all at least the difunctional polyisocyanates. The polyisocyanates contemplated are, for example, all of the polyisocyanates referred to when describing the polyisocyanates for preparing the hot melt polyurethane functionalized prepolymer of the invention.

The continuous mixing of the hydroxyl-functionalized polyurethane-based hot-melt prepolymer, melted according to the invention with one or more at least difunctional polyisocyanates, preferably occurs in a continuously operating mixing assembly, preferably in an extruder, further. particularly a planetary roller or double screw extruder, or in a two-component heat-set measuring and mixing system. Connected cascades of continuous batch or batch assemblies are also appropriate. The design of the mixing assembly is preferably such that efficient mixing is ensured in a short residence time in the mixing assembly. The addition of the hot-melt functionalized polyurethane-based polyurethane prepolymer, melted according to the invention and at least the different polyisocyanates, can occur in an extruder in the same. location or in different locations, preferably in depressurized areas. It is beneficial for at least the difunctional polyisocyanates to be added in finely divided form to the thermofused polyurethane prepolymer of hydroxyl functionalized according to the invention, for example in the form of an aerosol or fine droplets, for example.

The hydroxyl-functionalized polyurethane-based pre-polymer according to the invention can also be heated in a two-component measuring and mixing system and be transported in the molten state, as component A, with heating, while at least the difunctional polyisocyanates they are transported as component B. Continuous mixing then occurs in a dynamic mixing head or, preferably, in a static mixing tube, or in a combination of dynamic and static mixing methods.

Optionally, during the continuous mixing of the hydroxyl-functionalized polyurethane pre-polymerized copolymer according to the invention, in the melt, with one or more at least the difunctional polyisocyanates, other formulation components can be mixed, such as, for example, fillers, microgranules, resins, especially adherent hydrocarbon resins, plasticizers, inhibitors of aging (antioxidants), light stabilizers, UV absorbers, rheological additives, and also other auxiliaries and adjuvants.

During and after the continuous mixing of the hydroxyl-functionalized polyurethane-prepolymer according to the invention, in the melt, with one or more at least difunctional polyisocyanates, the chemical reaction to form the cross-linked polyurethane progresses continuously. Without catalysis or with moderate catalysis with an appropriate catalyst, the reaction rate is sufficiently slow to allow the thermoplastic process for a certain period of time. During this time, which is generally in the region of minutes, the mixture that chemically reacts warm or hot, can be continuously shaped to form a film. After conformation has occurred, the film is cooled to room temperature, causing it to solidify immediately, regardless of the progress of the chemical crosslinking reaction. Even at room temperature, the crosslinking reaction further progresses until the totality is achieved. At room temperature, the chemical crosslinking reaction is completely completed after, generally one to two weeks. After the complete reaction, the resulting polymer is generally crosslinked to such an extent that it is no longer meltable.

Continuous shaping of the hot, warm chemically reactive mixture occurs preferably through roller application means or by means of an extrusion die, but it can also occur with other application methods, such as, for example, a doctor blade. The shaped film is applied continuously to an incoming membrane of carrier material, and is subsequently rolled up. The incoming membrane of carrier material can be, for example, an anti-adhesive treated film or an anti-adhesive treated paper. Alternatively it can be a material already coated with. a sensitive adhesive. under pressure or with a functional layer, or it can be a carrier, or it can be any desired combination of the indicated membrane materials.

Since the thermofused polyurethane prepolymer with hydroxyl according to the invention already contains branches, the person skilled in the art must accept that, after the measured addition of the polyisocyanate to this prepolymer in the melt, ie at very high temperatures. from the ambient temperature, immediate gelling begins, in this case, immediately, the crosslinked structures which make it impossible to perform the additional mixing and coating and subsequent shaping to form the film. The fact that this did not happen was unforeseen for the person skilled in the art.

Since, as a result of the coating, the The film's spin-off is not linked to the progress of a chemical reaction or the rate of evaporation of a solvent, but instead only to the speed with which the film cools, it is possible to achieve very high coating speeds, and this it constitutes an economic advantage. In addition, there are no costs incurred to heat a section of the heating tunnel or to incinerate the solvent or recover the solvent. Since the hydroxyl-functionalized polyurethane-based hot-melt prepolymer of the invention can be prepared without solvent, there are no costs incurred for the incineration or recovery of solvent.

As a result of the possibility of absence of the solvent, it is possible in principle to produce polymer films of any desired thickness, without foaming or bubbling due to the evaporation of the solvent.

With the process of the invention it is possible in particular to produce very homogeneous thick layers (homogenously crosslinked) and homogeneously cross-linked three-dimensional shaped structures. Homogeneous thick layers of more than 100 μ, even greater than 200 μm, can be extraordinarily produced.

The process established above is especially appropriate for introducing viscoelastic adhesive tapes (single-layer constructions or constructions of multiple layers, with two or three layers, for example) that have a thickness between 100 μp? and 10 000 μp ?, preferably between 200 μ? and 5000 μt ?, more preferably between 300 μ? and 2500 μ ?? Because the continuous mixing of the polyisocyanate or polyisocyanates leading to an approximate chemical crosslinking only occurs immediately before shaping the mixture to form the film, it does not require blocking of reactive groups, and therefore does not need to use blocking agents . Therefore, at no time in time is there a release of blocking agents that remain in the film that could possibly be detrimental in the subsequent application.

The hot-melt polyurethane prepolymer functionalized with hydroxyl according to the invention can also be stored or prepared in a solvent or a mixture of solvents. In a solvent or mixture of solvents it can also be reacted with one or more polyisocyanates and coated with a solution during the start of the reaction phase between the polymer and the polyisocyanates. Examples of suitable solvents are methyl ethyl ketone, acetone, butyl acetate, decalin or tetrahydrofuran.

Since the lattice is not initiated from the outside by radiation, such as UV or EBC radiation, for example, a polymer structure with properties Consistently homogeneous is obtained even when the film produced is very thick or when the film includes considerable amounts of, for example, 50% or more.

As a result of the fact that, as a general rule, the average molar weight of the hydroxyl-functionalized polyurethane pre-polymerized hot-melt prepolymer according to the invention is low compared to a number of thermoplastically processable polymers, it can be melted and thermoplastically processed. comparatively low temperatures. During and after the formation of the melt to form a film, there is, as a general rule, technically relevant differences in the film in the longitudinal and transverse directions.

Surprisingly and also unpredictably for a person skilled in the art, the branching of the hydroxyl-functionalized polyurethane-based polyurethane prepolymer of the invention allows the generation of cross-linked polymer structures having fractions that can flow at the same time. Polymer structures of this type result in viscoelastic properties of the type required in the. sector of adhesive tapes in order to obtain high bonding resistances in conjunction with high resistance to. shearing. A certain degree of viscous flow is always necessary, as is known, to develop adhesion to substrates that will be joined. Of equal In this way, a certain degree of elastic resistance forces (cohesion) is necessary in order to have the ability to resist shear forces, especially under hot conditions. Suitable pressure sensitive adhesion properties can be obtained not only when the pressure sensitive adhesive layer is designed with the corresponding viscoelasticity, but also when applied with respect to the other layers of adhesive tape, such as the carrier layer or the adhesive layer. primer layer, for example. The unbranched hot-melt prepolymers, on the other hand, after crosslinking, result in any in polymer structures having a particularly elastic character, without significant flowable fractions, if not in polymer structures having fractions that can very highly flow and very inelastic fractions. An appropriate grade for PSA applications may not be adequately achieved in this way. The polymers with sufficient elasticity have a fluidity character on substrates only to a very low degree, and therefore develop only low adhesion forces. Where the unbranched hot-melt prepolymers, in turn, are cross-linked only slightly or not at all, therefore, they have a very low elastic character, and result in very low cohesive forces.

The thermofused polyurethane prepolymer The hydroxyl-functionalized compound of the invention can also be conveniently cross-linked with isocyanates that are only difunctional.

The invention is also described in greater detail with reference to the following examples without wishing thereby to restrict the invention.

The following test methods were used in order to briefly characterize the specimens according to the invention: Dynamic Mechanical Analysis (DMA) to determine the storage module G 'and the loss module G' ' In order to characterize hydroxyl-functionalized polyurethane prepolymers, the determinations of the storage modulus G 'and the loss modulus G "were carried out by means of a Dynamic Mechanical Analysis (DMA).

The measurements were made using a Rheometric Scientific DSR 200 N controlled shear stress rheometer in an oscillation experiment with a sinusoidal oscillating shear stress in a plate / plate array. The storage module G 'and the loss module G' 'were determined at a scanning frequency of 10"1 to 102 rad / sec at a temperature of 25 ° C. G' and G" are defined as follows: G ' (d) (T = shear stress,? = deformation, d = phase angle = phase change between shear stress vector and strain vector).

G '' = T / Y * sin (d) (T = shear stress,? = Deformation, d = phase angle = phase change between shear stress vector and strain vector).

The definition of angular frequency is as follows:? = 2n · f (f = frequency). The unit is rad / sec.

The thickness of the measured samples was always between 0.9 and 1.1 mm (1 + 0.1 mm). The sample diameter was in each case 25 mm. The prestressing took place with a load of 3N. For all measurements, the effort of the sample bodies was 2500 Pa.

Dynamic Mechanical Analysis (DMA) to determine the complex viscosity (? *) To characterize hydroxyl-functionalized polyurethane thermoformed prepolymers, complex viscosity determinations were performed by means of a Dynamic Mechanical Analysis (DMA).

The measurements were made using a Rheometric Scientific DSR 200 N controlled shear stress rheometer in an oscillation experiment with a sinusoidal oscillating shear stress in a plate / plate-array. The complex viscosity was determined in a temperature sweep from -50 ° C to + 250 ° C with a frequency oscillation 10 rad / s. The complex viscosity n * is defined as follows:? * = T * /? (G * = complex shear modulus,? = Angular frequency).

The additional definitions are as follows: (G '' = viscosity module (loss modulus), G '= modulus of elasticity (storage modulus)).

G '' = T / Y «sin (d) (T = shear stress,? = Deformation, d = phase angle = phase change between the shear stress vector and deformation vector).

G ' (d) (T = shear stress,? deformation, d = phase angle = phase change between the shear stress vector and strain vector). ? = 2n · f (f = frequency).

The thickness of the samples measured was always between 0.9 and 1.1 mm (1 ± 0.1 mm). The sample diameter was in each case 25 mm. The prestressing took place with a load of 3N. For all measurements, the effort of the sample bodies was 2500 Pa.

Determination of stress properties in the tensile strength test After storage for two weeks at room temperature, the samples, with a thickness of 0.9 to 1.1 mm, were investigated in the longitudinal direction (direction of shaped) and in the transverse direction (direction at an angle of 90 ° relative to the forming direction in the film plane) with respect to its tensile strength properties.

The measurements were taken in accordance with DIN EN ISO 527-1 to 3 in the standard test specimens of size 5A with a test speed of 300 mm / min. The tension stress and the associated resistance were measured. The tensile strength is the maximum force measured on the tension of the test material, divided by the initial cross-sectional area of the sample, and is reported in units N / mm2. The tension in the tensile strength is the change in length, in relation to the originally measured length of the test strip, at the maximum measured force, and is reported in units%.

Determination of relaxation behavior After a storage time of two weeks at room temperature, the samples, with a thickness of 0.9 to 1.1 mm, were investigated in the longitudinal direction (shaping direction) and in the transverse direction (direction at an angle of 90 ° in relationship with the forming direction in the film plane) with respect to its relaxation behavior. The investigations of the relaxation behavior were similarly carried out in a resistance test to tension in accordance with DIN EN ISO 527-1 to 3 using standard test specimens of size 5A. At a test speed of 100 mm / min, the test material was stretched by 50% in the longitudinal direction, in relation to the original length of the test strip. The associated effort was measured at the moment when the tension reached 50%. The stress is defined as the tensile force on the sample body, in relation to the initial cross-sectional area within the measured length. The 50% effort was maintained additionally. After a time of five minutes, the effort was determined again. The percentage decrease in effort is relaxation: relaxation = 100 x (initial effort - final effort) / initial effort.

Gel Permeation Chromatography (GPC) In order to characterize hydroxyl-functionalized polyurethane hot melt prepolymers, average number and weight determinations of average molar masses were performed by means of gel permeation chromatography (GPC). The measurements were developed under the premises of the Polymer Standards Service Company in Mainz.

The calibration took place universally with poly (methyl methacrylate). The determinations were made in accordance with the method AM 1005. The eluent used was THF / 0.1% by volume of trifluoroacetic acid (TFAc). The column previously used was PSS-SDV, 10 im, ID 8.0 mm x 50 mm, and the column used was PSS-SDV, ?? μp? one linear, ID 8.0 x 300 mm. A TSP P 100 was used for pumping. The flow rate was 0.5 ml / min. The sample concentration was around 1.5 g / 1. The injection system was a TSP AS 3000. The injection volume was 100 μ? . The measurement took place at 23 ° C. The detector was a Shodex RI 71. The evaluation was performed using the PSS-WinGPC Unity Version 7.20 program.

Bond strength The binding strength was determined in accordance with PSTC-101. In accordance with this method, the adhesive strip for the measurement was applied to the substrate (steel), pressing twice with a weight of 2 kg and then detached under conditions defined by means of a tension testing machine. The detachment angle was 90 ° or 180 °. The speed of detachment 300 mm / min. The force required for detachment by detachment is the bond strength, which is reported in units N / cm. The measured adhesive strips were reinforced with a 25 μp polyester film backing. -Shearing test The shear test was carried out in accordance with the PSTC-107 test specification. In accordance with this method, the adhesive strip for measurement was applied to the substrate (steel), pressed four times using a 2 kg weight, and then exposed to a constant shear load. The support time is set, in minutes.

The area of connection was in each case 13 x 20 mm2. The shear load in this joint area was 1 kg. The measurement was carried out at room temperature (23 ° C). The measured adhesive strips were reinforced with a support of a 25 μ polyester film.

The hydroxyl functionalized polyurethane prepolymers were manufactured in a customary thermal form and mixing vessels that can be emptied with stirring mechanism to dissolve, from the Olteni company. During the mixing operation, which lasted approximately two hours in each case, the temperature of the mixture was adjusted to approximately 70 ° C to 100 ° C. In cases where no solvent was used, vacuum was applied in order to degas the components.

The reaction of the hydroxyl-functionalized polyurethane hot-melt prepolymers according to the invention took place with one or more polyisocyanates, in the cases where the hydroxyl-functionalized polyurethane-based hot-melt prepolymer was used in its function as a hot-melt, in an extruder of double screw from the company Leistritz, Germany, ref. LSM 30/34. The assembly was electrically heated from the outside to approximately 70 ° C at 90 ° C and was cooled by air by a variety of fans, and was designed to ensure efficient mixing of the prepolymer and polyisocyanate with a short residence time in the extruder. For this purpose, the mixing screws of the double screw extruder were arranged so that the carrying elements alternate with the mixing elements. The respective polyisocyanate was added with appropriate dosing equipment, using dosing assistants, within the non-pressurized transport zones of the double screw extruder.

After the chemically reactive mixture, with a temperature of about 80 ° C, has emerged from the double screw extruder (outlet: 5 mm diameter circular nozzle), its conformation in a film takes place directly by means of a application unit of double roller downstream, between two incoming films, polyester 50 μ ?? with silicone on two sides. The feeding speed was varied between 1 m / min and 20 m / min. After the film was cooled and therefore solidified, one of the incoming polyester films, with silicone on two sides, was immediately removed again. This then provided a roll-up film.

Some of the films rolled on the polyester film with silicone were unrolled again after a period of two weeks of storage at temperature environment, and laminated with the pressure sensitive polyacrylate adhesive Durotac 280-1753 from the company National Starch, which was present in the form of an outer coating adhesive prepared in a thickness of 50 μt? on the siliconized polyester film. The lamination took place without additional pretreatment. The experiments with the polyacrylate PSA served to prove its use as a carrier layer or as a functional layer in an adhesive tape.

In some of the experiments, the thermofused polyurethane-functionalized hydroxyl prepolymers according to the invention were dissolved in acetone before being used. The acetone fraction was always 40% by weight. The reaction of the hydroxyl-functionalized polyurethane hot-melt prepolymers according to the invention with one or more polyisocyanates then takes place in a customary manner, mixing vessels that can be heated and evacuated with stirring mechanism for dissolving, from the company Molteni, to room temperature. The mixing time was 15 to 30 minutes. A chemically reactive mixture of this type, comprising a hot melt polyurethane prepolymer functionalized with hydroxyl with one or more polyisocyanates, in acetone, could be coated for approximately 24 to 48 hours in general, with catalyst levels between 0.05% and 0.2. %, until a gradual gelation occurred.

Table 1 lists the base materials used to produce the chemically cross-linked polyurethane film, in each case with the commercial name and manufacturer. The established raw materials can be freely purchased commercially.

Number- Number of OH or NCO mass Molar name (mmol Manufacturer Chemical bases average commercial OH / kg or / supplier Mn mmol (g / mol) NCO / ko) Propylene glycol , Voranol P400® 400 4643 Dow diol Propylene glycol , Voranol 1010L® 1000 1961 Dow diol Propylene glycol , Voranol 2000L® 2000 989 Dow diol Voranol CP Propylene glycol, 1000 2781 Dow 1055® triol Voranol CP Propylene glycol, 3500 847 Dow 3355® triol Voranol CP Propylene glycol, 6000 491. Dow .6055® triol 2-Methyl-l, 3- MPDiol® 90.12 22 193 Lyonde11-propanediol Ethylene glycol Ethylene glycol 62.07 32 222 Aldrich Alcohol of process-oxo Lutensol A07® 520 1961 BASF C13C15 ethoxylated Table 1: Base materials used to produce chemically cross-linked polyurethane films Eg emplos Example 1 The thermofused polyurethane prepolymer, functionalized with hydroxyl, was prepared by homogeneous mixing and therefore by chemically reacting the following starting materials in the specified proportions: Fraction Material Proportion Proportion Proportion percentage weight percentage percentage (% by the number of the number of the weight number) of OH groups molecules that molecules with one another carry groups functionalizaOH one with each other (idealized) * (idealized) * Voranol P400 21.7 42.0 43.4 22.5 Voranol CP 48. 9 10.0 6.9 3.6 6055 MP Diol 5.2 48.0 49.7 25.7 Coscat 83 0.1 Vestanat 24. 1 48.2 IPDI Total 100.0 100.0 100.0 100.0 Table 2: Composition of hydroxyl-functionalized polyurethane hot-melt prepolymer, Example 1 ? calculated from the weight fractions and the OH numbers or NCO numbers of the starting materials, under the highly idealized assumption that the Voranol P 00 has a functionality of exactly 2, and that the Voranol CP 6055 has a functionality of exactly 3.

To begin with, all the starting materials listed, apart from MP Diol and Vestanat IPDI, were mixed at a temperature of 70 ° C and a pressure of 100 mbar for 1.5 hours. The MP Diol was then mixed for 15 minutes, and then the Vestanat IPDI, in the same way for a period of 15 minutes. As a result of the heat of reaction produced, the mixture underwent heating at 100 ° C, and was then poured into storage containers.

The NCO / OH ratio was 0.90. The theoretical gel point is calculated as 0.91. The 10% of the droxyl groups introduced to form the thermofused polyurethane prepolymer functionalized with Mdroxil originated from a polypropylene glycol having a functionality of more than two and an average molar mass number of 6000 g / mol. Therefore about 6.9% of starting material molecules carrying trifunctional OH groups. Above all, in an idealized consideration, 3.6% of the molecules involved in the molecular construction of the hydroxyl-functionalized polyurethane hot-melt prepolymer are trifunctional and therefore capable of forming branched structures. 96. 4% of the molecules involved in the construction The molecular weight of the hydroxyl-functionalized polyurethane hot-melt prepolymer has a relative molar mass of less than or equal to 1000 (in an idealized consideration).

The resulting prepolymer solidifies at room temperature and in terms of consistency was rubbery and sticky (pressure sensitive adhesive). The complex viscosity? * At room temperature (23 ° C) was 18,000 Pas and at 70 ° C it was 210 Pas.

The weight of average molar mass Mw was 120,000 g / mol, the average molar mass number Mn was 17 600 g / mol.

The resulting prepolymer was meltable.

For some of the experiments the prepolymer was dissolved in acetone.

Use: To produce a pressure sensitive adhesive (PSA) film, the prepolymer in solution in acetone was coated at room temperature on a 25 μm thick polyester film. The solvent was evaporated at 70 ° C. This provided a 50 μp layer? of thickness.

To produce a carrier of chemically crosslinked adhesive tape, the prepolymer was fed continuously to a twin screw extruder preheated to 80 ° C. The polyisocyanate was metered into the twin screw extruder continuously at the same time and in the same place. The metered polyisocyanate used was Desmodur W (dicyclohexylmethane diisocyanate).

Again, a total proportion of the NCO / OH of 1. 05 The mixing ratios were therefore as follows: 100 parts by weight of prepolymer: 4.54 parts by weight of Desmodur W.

Mixing and transportation were carried out continuously. The time occupied by the extrudate to leave the extruder was around two minutes.

The extrudate was supplied directly to a double roller applicator, where it was coated between two incoming films, polyester with silicone on two sides and thereby forming a film. The thickness of the film was 1.0 mm. After cooling to room temperature and subsequent removal of one of the two silicone polyester films, the film was rolled up. The rolled film was stored at room temperature for two weeks.

This was again partially unrolled and laminated to Polyacrylate PSA Durotac 280-1753 from National Starch, present in a coating form prepared on the polyester film with silicone at a thickness of 50 μm. The lamination took place without a pretreatment at all. Experiments with the PSA Durotac polyacrylate were used to test their uses as a carrier layer or as a functional layer on an adhesive tape.

The test results (Example 1) are summarized in the table following : Prepolymer Prepolymer Prepolymer Prepolymer hot-melt after the after-reaction after the reaction crosslinking and polyurethane (crosslinking) (crosslinking) lamination to the functionali- in solution with in the polyacrylate melt with IPDI with Desmodur W PSA Durotac hydroxyl 280- 1753 Deformation, longitudinal > 1000 .630 580 (%) Deformation, cross section > 1000 670 570 (%) Relaxation, longitudinal > 90 55 51 (%) Relaxation, cross section > 90 57 50 (%) 11. 6 Resistance (angle 18.3 (joint angle, 5.3 (angle of 4.8 (angle of of steel, 300 detached, I learned detachment / min. -miento: ment: 90 °) (N / cm) 180 °) Time of support in the test of cizallamient or at 11 7500 > 10000 > 10000 temperature environment, 1 kg load (min) Table 3: Test results, Example For comparison, the binding strength of the Durotac PSA 280-1753, applied as a 50 μp layer? of thickness to a 25 μ polyester film ?? of thickness was 5.9 N / cm.

Example 2 The hot-melt polyurethane-functionalized prepolymer with hydroxyl fe prepared by a homogeneous mixing and therefore by chemically reacting the starting materials in the specified proportions: Table 4: Composition of the hydroxyl-functionalized polyurethane hot-melt prepolymer, Example 2 * calculated from the weight fractions and numbers NCO numbers of the starting materials, under the highly idealized assumption that the Voranol P 00 has a functionality of exactly 2, and that the Voranol CP 6055 has a functionality of exactly 3.

To begin with, all the starting materials listed, apart from MP Diol and Desmodur, were mixed at a temperature of 70 ° C and a pressure of 100 mbar for 1.5 hours. The MP Diol was then mixed for 15 minutes, and then the Desmodur W, in the same way for a period of 15 minutes. As a result of the heat of reaction produced, the mixture underwent heating at 100 ° C, and was then poured into storage containers.

The NCO / OH ratio was 0.97. The theoretical gel point is calculated as 0.98. 2.5% of the hydroxyl groups introduced to form the thermofused polyurethane-hydroxyl-functionalized prepolymer originated from a polypropylene glycol having a functionality of more than two and an average molar mass number of 6000 g / mol. Therefore about 1.7% of starting material molecules carrying OH groups are trifunctional. Above all, in an idealized consideration, .0.8% of the molecules involved in the molecular construction of the hydroxyl-functionalized polyurethane hot-melt prepolymer are trifunctional and therefore capable of forming branched structures. 99.2% of the molecules involved in the molecular construction of the hydroxyl-functionalized polyurethane hot-melt prepolymer have a relative molar mass of less than or equal to 1000 (in a idealized).

The resulting prepolymer was solidified at room temperature and in terms of consistency it was rubbery and sticky (pressure sensitive adhesive). The complex viscosity? * At room temperature (23 ° C) was 54,000 Pas and at 70 ° C it was 265 Pas.

The average molar mass weight Mw was 100 000 g / mol, the average molar mass number Mn was 15 600 g / mol.

The resulting prepolymer was meltable.

For some of the experiments the prepolymer was dissolved in acetone.

To produce a chemically cross-linked PSA, the prepolymer in solution in acetone was mixed at room temperature with Vestanat IPDI. The mixing ratio was 100 parts by weight of prepolymer: 2.51 parts by weight of Vestanat IPDI. The total NCO / OH ratio of all the NCO and OH groups was introduced to the point where it was therefore 1.05. The mixture was coated on a polyester film of 25 μP? of thickness. The solvent was evaporated at 70 ° C. This provided a layer of 50 μp? of thickness.

To produce a chemically crosslinked adhesive tape carrier, the prepolymer was fed continuously to a twin screw extruder preheated to 80 ° C. The polyisocyanate was metered into the twin screw extruder continuously at the same time and in the same place. The metered polyisocyanate used was the Vestanat IPDI.

Again, a total NCO / OH ratio of 1. 05 The mixing ratios were therefore again as follows: 100 parts by weight of prepolymer: 2.51 parts by weight of Vestanat IPDI.

Mixing and transportation were carried out from. continuous way The time taken to extrude to leave the extruder was around two minutes.

The extrudate was supplied directly to a double roller applicator, where it was coated between two incoming films, polyester with silicone on two sides and thereby form a film form. The thickness of the film was 1.0 mm. After cooling to room temperature and subsequent removal of one of the two silicone polyester films, the film was rolled up. The rolled film was stored at room temperature for two weeks.

This then was again partially unrolled and laminated to Polyacrylate PSA Durotac 280-1753 from National Starch, present in a form of coating prepared on the polyester film with silicone in a thickness of 50 μp ?. The lamination took place without a pretreatment at all. Experiments with PSA polyacrylate were used to test their uses as a carrier layer or as a functional layer on an adhesive tape.

The test results (Example 2) are summarized in the following table: prepolymer Prepolymer Prepolymer Prepolymer ro after the after the after the thermofunctioning reaction crosslinking and dido (crosslinking) (crosslinking) lamination to the polyuret in solution in the polyacrylate melt -no with IPDI with IPDI PSA Durotac works- 280-1753 lizado with hydroxyl G '(in 1 50 000 370 000 390 000 rad / sec and 25 ° C) (Pa) G "(in 1 110 000 320 000 320 000 rad / sec and 25 ° C) G '(in 10 270 000 610 000 650 000 rad / sec and 25 ° C) G "(in 10 400 000 450 000 520 000 rad / sec and 25 ° C) Resistance 0.1 1.4 1.6 to tension, longitudinal (N / mm2) prepolymer Prepolymer Prepolymer Prepolymer or after the after the after the thermof a reaction reaction crosslinking and dido of (crosslinking) (crosslinking) lamination to the polyurethane-in solution with in the non-IPDI polyacrylate melt with IPDI PSA Durotac works - 280- 1753 lizado with hydroxyl Resistance 0.1 1.3 1.4 to tension, cross (N / mm2) Deformation, > 1000 800 630 longitudinal (%) Deformation, > 1000 670 650 cross (%) Relaxation, > 90 48 51 longitudinal (%) Relaxation, > 90 49 50 cross (%) Resistance 12.8 5.9 (angle 4.9 (angle 34.7 (angle of attachment, (angle of detached detachment, 300 of detachment: 180 °) measurement: 90 °) rnm / min detachment: (N / cm) depth: 180 °) 180 °) Time of 16 350 800 900 support in the test of shearing to temperature environment, 1 kg load (min) Table 5: Test results, Example 2 For comparison, the binding strength of the Durotac PSA 280-1753, applied as a layer of 50 μ? T? of thickness to a 25 μp polyester film? of thickness was 5.9 N / cm.

Example 3 The thermofused hydropolylated polyurethane prepolymer was prepared by a homogeneous mixing and therefore by chemically reacting the starting materials in the specified proportions: Table 6: Composition of the hydroxyl-functionalized polyurethane hot-melt prepolymer, Example 3 ? calculated from the weight fractions and the numbers OH or NCO numbers of the starting materials, under the highly idealized assumption that the Voranol 1010L and the Voranol P400 have a functionality of exactly 2, and that the Voranol CP 3355 has a functionality of exactly 3.

To begin with, the total listed starting materials, apart from the Vestanat IPDI, were mixed at a temperature of 70 ° C and a pressure of 100 mbar for 1.5 hours. The Vestanat IPDI was then mixed for a time of 15 minutes. As a result of the heat of reaction produced, the mixture underwent heating at 100 ° C, and was then poured into storage containers.

The NCO / OH ratio was 0.98. The theoretical gel point is calculated as 0.98. 2.0% of the hydroxyl groups introduced to form the hydroxyl-functionalized polyurethane hot melt prepolymer originated from a polypropylene glycol having a functionality of more than two and an average molar mass number of 3500 g / mol. Therefore about 1.3% of the starting material molecules carrying OH groups are trifunctional. Above all, in an idealized consideration, 0.7% of the molecules involved in the molecular construction of the hydroxyl-functionalized polyurethane hot-melt prepolymer are trifunctional and therefore capable of forming branched structures. 99.3% of the molecules that participate in the molecular construction of hydro-fused functionalized polyurethane prepolymer have a relative molar mass less than or equal to 1000 (in an idealized consideration).

The resulting prepolymer was solidified at room temperature and in terms of consistency it was rubbery and sticky (pressure sensitive adhesive). The complex viscosity? * At room temperature (23 ° C) was 36,000 Pas and at 70 ° C it was 95 Pas.

The average molar weight w was 99,000 g / mol, the average molar mass Mn was 13 600 g / mol.

The resulting prepolymer was meltable.

For some of the experiments the prepolymer was dissolved in acetone.

Use: To produce a film of pressure sensitive adhesive (PSA), the prepolymer in solution in acetone was coated at room temperature on a polyester film of 25 μp? of thickness. The solvent was evaporated at 70 ° C. This provided a layer 50 m thick.

To produce a chemically cross-linked PSA, the prepolymer in solution in acetone was mixed at room temperature with Desmodur. The mixing ratio was 100 parts by weight of prepolymer: 2.16 parts by weight of Desmodur W. The total NCO / OH ratio of the total of the NCO and OH groups introduced to the point where it was therefore 1.05. The mixture was coated on a 25 μm thick polyester film. The solvent was evaporated at 70 ° C. This provided a 50 μp layer? of thickness.

To produce a carrier of chemically crosslinked adhesive tape, the prepolymer was fed continuously to a twin screw extruder preheated to 80 ° C. The polyisocyanate was metered into the twin screw extruder continuously at the same time and in the same place. The dosed polyisocyanate used was the Desmodur W.

Again, a total NCO / OH ratio of 1. 05 The mixing ratios were therefore again as follows: 100 parts by weight of prepolymer: 2.16 parts by weight of Desmodur.

Mixing and transportation were carried out continuously. The time taken for the extrudate to leave the extruder was around two minutes.

The extrudate was supplied directly to a double roller applicator, where it was coated between two incoming films, polyester with silicone on two sides and thereby form a film form. The thickness of the film was 1.0 mm. After cooling to room temperature and subsequent removal of one of the two polyester films with silicone, the film was rolled up. The rolled film was stored at room temperature for two weeks.

This then was again partially unrolled and laminated to Polyacrylate PSA Durotac 280-1753 from National Starch, present in a form of coating prepared on the polyester film with silicone in a thickness of 50 um. The lamination took place without a pretreatment at all. Experiments with PSA polyacrylate were used to test their uses as a carrier layer or as a functional layer on an adhesive tape.

The test results (Example 3) are summarized in the following table: Prepoly mePrepolymer Prepolymer Prepolymer ro after the after the after the termofundi reaction crosslinking reaction and -do of (crosslinking) (crosslinking) in lamination to the polyuret- in solution with the polyacrylate melt PSA no Desmodur W Desmodur Durotac 280-1753 functionalized with hydroxyl G '(in 1 9000 90 000 100 000 rad / sec and 25 ° C) (Pa) G "(in 1 28 000 88 000 95 000 rad / sec and 25 ° C) G '(in 10 65 000 250 000 270 000 rad / sec and 25 ° C) G "(in 10 110 000 150 000 160 000 rad / sec and 25 ° C) Resistance < 0.1 0.7 0.8 to tension, longitudinal (N / mm2) Prepollme- Prepolymer Prepolymer Prepolymer ro after the after the after the termof undi reaction reaction crosslinking and -do of (crosslinking) in (crosslinking) lamination to the polyurethane solution with in the polyacrylate melt PSA no Desmodur W with Desmodur W Durotac 280 -1753 f unicated with hydroxyl Resistance < 0.1 0.6 0.8 to tension, cross (N / mm2) Deformation, > 1000 400 450 longitudinal (%) Deformation, > 1000 390 470 cross (%) Relaxation, > 90 42 41 longitudinal (%) Relaxation, > 90 40 42 cross (%) Resistance 8.0 1.3 (angle 0.9 (angle 15.0 (joint angle, (detaching angle, 300 degree of movement: 180 °) detachment: 90 °) mm / min (N / cm) detachment: -standing: 180 °) 180 °) Time of < 1 260 250 320 support in test shearing to temperature environment, 1 kg load (min) Table 7: Test results, Example 3 For comparison, the bond strength of Durotac PSA 280-1753, applied as a 50 μm thick layer to a 25 μm thick polyester film was 5.9 N / cm.

Example 4 The hydroxyl-functionalized polyurethane hot-melt prepolymer was prepared by homogeneous mixing and therefore by chemically reacting the starting materials in the specified proportions: Table 8: Composition of the hydroxyl-functionalized polyurethane hot-melt prepolymer, Example 4 ? calculated from the weight fractions and the OH numbers or NCO numbers of the starting materials, under the highly idealized assumption that the Voranol P400 and the Voranol 2000L have a functionality of exactly 2, and that the Voranol CP 6055 has a functionality of exactly 3. For the Lutensol A07, a functionality of 1 was assumed.

To begin with, all the starting materials listed, apart from ethylene glycol and Vestanat IPDI, were mixed at a temperature of 70 ° C and a pressure of 100 mbar for 1.5 hours. The ethylene glycol was then mixed for 15 minutes, and then the Vestanat IPDI, for a period of 15 minutes. As a result of the heat of reaction produced, the mixture underwent heating at 100 ° C, and was then poured into storage containers.

The NCO / OH ratio was 0.92. The theoretical gelling point is calculated as 0.92 when the Lutensol A07 is not included in the calculation. 8.6% of the hydroxyl groups introduced to form the hydroxyl-functionalized polyurethane hot melt prepolymer originated from a polypropylene glycol having a functionality of more than two and an average molar mass number of 6000 g / mol. Therefore about 5.8% of starting material molecules carrying OH groups are trifunctional Above all, in an idealized consideration, 3.0% of the molecules involved in the molecular construction of the hydroxyl-functionalized polyurethane hot-melt prepolymer are trifunctional and therefore capable of forming branched structures. 92.4% of the molecules involved in the - molecular construction of the hydroxyl-functionalized polyurethane hot melt prepolymer have a relative molar mass less than or equal to 1000 (in an idealized consideration).

The resulting prepolymer was solidified at room temperature and in terms of consistency it was rubbery and sticky (pressure sensitive adhesive). The complex viscosity n * at room temperature (23 ° C) was 75,000 Pas and at 70 ° C it was 650 Pas.

The weight of average molar mass Mw was 130 000 g / mol, the average molar mass number Mn was 15 900 g / mol.

The resulting prepolymer was meltable.

Use: The prepolymer this time was used exclusively to produce a carrier of viscoelastic, chemically cross-linked adhesive tape.

For this purpose, it was supplied continuously to a double screw extruder preheated to 80 ° C. The polyisocyanate was metered into the extruder of Double screw continuously at the same time and in the same place. The metered polyisocyanate used was the Vestanat IPDI.

A total NCO / OH ratio of 1.Ó5 was established. The mixing ratios were therefore as follows: 100 parts by weight of prepolymer: 2.90 parts by weight of Vestanat IPDI.

This was then again partially unrolled and laminated to PSA Durotac 280-1753 polyester from National Starch, present in a coating form prepared on the polyester film with silicone in a thickness of 50 μm. The lamination took place without a pretreatment in absolute. Experiments with PSA polyacrylate were used to test their uses as a carrier layer or as a functional layer on an adhesive tape.

The test results (Example 4) are summarized in the following table: prepolymer Prepolymer Pre-polymer hot-melt after the polyurethane reaction after crosslinking and functionalized (crosslinking) in lamination with hydroxyl the polyacrylate PSA melt (film of 1 Vestanat IPDI Durotac 280-1753 mm thick) (1 mm film of thickness) G '(in 1 11 000 100 000 rad / sec and 25 ° C) (Pa) G "(in 1 31 000 85 000 rad / sec and 25 ° C) G '(in 10 95 000 270 000 rad / sec and 25 ° C) G "(in 10 150 000 240 000 rad / sec and 25 ° C) Resistance to 0.1 1..1 the tension, longitudinal (N / mm2) Prepolymer Prepolymer Pre-polymer hot-melt after the polyurethane reaction after crosslinking and functionally lifting (crosslinking) in lamination with hydroxyl the polyacrylate PSA melt (film of 1 Vestanat IPDI Durotac 280-1753 mm thick) (1 mm film of thickness) Resistance to 0.1 1.1 the tension, cross (N / mm2) Deformation, > 1000 770 longitudinal (%) Deformation, > 1000 750 cross section (%) Relaxation, 85 56 longitudinal (%) Relaxation, 86 57 cross section (%) Resistance of 11.1 (angle 4.1 (angle of 29.0 (joint angle, steel, detachable - 300 mm / min detachment: 90 °): 90 °) (N / cm) to: 90 °) Time of 13 6000 > 10,000 support in the test shearing to temperature environment, 1 kg Load (min) Table 9: Test results, Example 4 For comparison, the binding strength of the Durotac PSA 280-1753, applied as a 50 μp layer? of thickness to a polyester film of 25 μm thickness, was 5.9 N / cm.

Comparative Example 1 A hydroxyl functionalized polyurethane pre-polymer was prepared by homogeneous mixing and therefore chemically reacting the following starting materials in the specified proportions: Fraction Material Proportion Proportion Weight percentage percentage percentage (% by number of number of weight number) of OH groups molecules that molecules with one another carry groups functionalizaOH one with one another (idealized) * (idealized) * Voranol P400 36.3 42 43.5 22.5 Voranol CP 14. 4 10 6.9 3.6 1055 MP Diol 8.7 48 49.6 25.7 Coscat 83 0.1 Vestanat 40. 5 48.2 IPDI Total 100.0 100.0 100.0 100.0 Table 10: Composition of the hydroxyl-functionalized polyurethane hot-melt prepolymer, Comparative Example 1 * calculated from the weight fractions and the OH numbers or NCO numbers of the starting materials, under the highly idealized assumption that the Voranol P400 has a functionality of exactly 2, and that the Voranol CP 1055 has a functionality of exactly 3.

To begin with, all the starting materials listed, apart from MP Diol and Vestanat IPDI, were mixed at a temperature of 70 ° C and a pressure of 100 mbar for 1.5 hours. The MP Diol was then mixed for 15 minutes, and then the Vestanat IPDI, in the same way for a period of 15 minutes. As a result of the heat of reaction produced, the mixture underwent heating at 110 ° C, and was then poured into storage containers.

The NCO / OH ratio was 0.91. The theoretical gel point is calculated as 0.91. 10% of the hydroxyl groups introduced to form the hot-melt polyurethane-based hydroxy-based polyurethane pre-polymer originated from a polypropylene glycol having an excess functionality. of two and a number of average molar mass of 1000 g / mol. Therefore, about 6.9% of the starting material molecules that carry OH groups are t i i fune i onal s. Above all, in an idealized consideration, 3.6% of the molecules involved in the molecular construction of the hydroxyl-functionalized polyurethane hot-melt prepolymer are functional and therefore capable of forming branched structures. 100% of the molecules that participate in the molecular construction of the hydroxyl-functionalized polyurethane hot melt prepolymer have a relative molar mass less than or equal to 1000 (in an idealized consideration).

The resulting prepolymer is solidified at room temperature with a brittle hardness, and in terms of consistency was not tacky (not pressure sensitive adhesive). The G 'both at 1 rad / sec and at 10 rad / sec was greater than 106 Pa, in each case at 25 ° C. The suitable properties for more convenient applications for PSA application were not displayed.

Comparative Example 2 The hydroxyl-functionalized polyurethane hot-melt prepolymer was prepared by homogeneous mixing and therefore by reacting chemically the following starting materials in the specified proportions: Table 11: Composition of polyurethane hot-melt prepolymer hydroxylated, Comparative Example 2 ? calculated from the weight fractions and the OH numbers or NCO numbers of the starting materials, under the highly idealized assumption that the Voranol P400 has a functionality of exactly 2.

To begin with, all the starting materials listed, apart from MP Diol and Vestanat IPDI, were mixed at a temperature of 70 ° C and a pressure of 100 mbar for 1.5 hours. The MP Diol then It was mixed for 15 minutes, and then the Vestanat IPDI, in the same way for a period of 15 minutes. As a result of the heat of reaction produced, the mixture underwent heating at 110 ° C, and was then poured into storage containers.

The ratio of.NCO / OH was 0.98. The theoretical gelation point is calculated as 1.0. The 0% of the hydroxyl groups introduced to form the hydroxyl-functionalized polyurethane-based polyurethane prepolymer originated from a polypropylene glycol having a functionality of more than two and an average molar mass number of 1000 g / mol. Therefore, there are no trifunctional starting material molecules. 100% of the molecules that participate in the molecular construction of the thermofused polyurethane prepolymer fused with hydroxyl have a relative molar mass less than or equal to 1000 (in an idealized consideration).

The resulting prepolymer is solidified at room temperature with a brittle hardness, and in terms of consistency was not tacky (not pressure sensitive adhesive). The G 'both at 1 rad / sec and at 10 rad / sec was greater than 106 Pa, in each case at 25 ° C. The viscoelastic properties suitable for PSA applications were not displayed.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. A hydroxyl-functionalized polyurethane-based prepolymer comprising the chemical reaction product of isocyanate-reactive starting materials with at least one isocyanate-containing starting material, characterized in that the isocyanate-reactive starting materials of the polyurethane-based hot-melt prepolymer hydroxyl comprise at least one polypropylene glycol PI having a functionality of more than two and an average molar mass number greater than or equal to 3000 g / mol, at least one polypropylene glycol PII having a functionality less than or equal to two and a number of average molar mass less than or equal to 1000 g / mol, at least one KI chain extender having a functionality less than or equal to two and an average molar mass number less than or equal to 500 g / mole; and in that the isocyanate-containing starting material of the hydroxyl-functionalized polyurethane hot-melt prepolymer is or comprises an aliphatic or alicyclic diisocyanate.

2. The hydroxyl-functionalized polyurethane-based precursor according to claim 1, characterized in that the numerical fraction of the hydroxyl groups which is introduced to form the thermofused polyurethane-functionalized hydroxyl prepolymer and originates from a polypropylene glycol PI is at least 2.5%, preferably at least 5.0% and / or no more than 25.0%, preferably not more than 20.0%.

3. The hydroxyl-functionalized polyurethane hot melt prepolymer according to any of claims 1 and 2, characterized in that the average molar mass number of the polypropylene glycol PI is greater than or equal to 4500 g / mol, preferably greater than or equal to 5500 g / mol .

4. The hydroxyl-functionalized polyurethane hot melt prepolymer according to any of the preceding claims, characterized in that the average molar mass number of the polypropylene glycol PII is less than or equal to 800 g / mol, preferably less than or equal to 600 g / mol.

5. The hydroxyl-functionalized polyurethane hot melt prepolymer according to any of the preceding claims, characterized in that the average molar mass number of the chain extender KI is less than or equal to 400 g / mol, preferably less than or equal to 200 g / mol.

6. The hydroxyl-functionalized polyurethane pre-polymerized copolymer according to claim 1, characterized in that the aliphatic or alicyclic diisocyanate is or comprises isophorone diisocyanate and / or dicyclohexyl-thiocyanate diisocyanate.

7. The hydroxyl-functionalized polyurethane hot melt prepolymer according to any of the preceding claims, characterized in that the ratio of the total number of isocyanate groups to the total number of hydroxyl groups of the substances involved in the chemical reaction to give the polyurethane hot melt prepolymer functionalized with hydroxyl is between greater than or equal to 0.80 and less than or equal to 0.98, preferably between greater than or equal to 0.85 and less than or equal to 0.97, more preferably between greater than or equal to 0.90 and less than or equal to 0.96.

8. A process for preparing a hydroxyl-functionalized polyurethane hot melt prepolymer according to any of the preceding claims, characterized in that the chemical reaction to give the hot-melt polyurethane prepolymer functionalized with hydroxyl occurs with the addition of a catalyst, more particularly a catalyst comprising bismuth and carbon, preferably a bismuth carboxylate or a bismuth carboxylate derivative.

9. The use of a hydroxyl-functionalized polyurethane-based polyurethane prepolymer according to any of claims 1 to 7, or of a hot-melt polyurethane prepolymer prepared according to claim 8 as a pressure-sensitive adhesive.

10. The use of a hydroxyl-functionalized polyurethane-based prepolymer according to any one of claims 1 to 7, or of a polyurethane hot-melt prepolymer prepared according to claim 8 as an adhesive tape carrier material and / or as a layer functional adhesive tape.

11. The use of a hydroxyl-functionalized polyurethane-based prepolymer according to any of claims 1 to 7, or of a polyurethane hot-melt prepolymer prepared according to claim 8 to produce polyurethane moldings and / or polyurethane layers by reaction in the melt with one or more polyisocyanates and shaping, more particularly coating.

12. The use according to claim 11, wherein the reaction product of the thermofused polyurethane prepolymer with the polyisocyanate or polyisocyanates has pressure sensitive adhesive properties.

13. Use in accordance with any of the claims 11 and 12, wherein the reaction of the thermofused polyurethane prepolymer with the polyisocyanate or polyisocyanates occurs without solvent, more particularly in the melt.

14. The use according to any of claims 11 to 13, wherein the reaction of the thermofused polyurethane prepolymer with the polyisocyanate or polyisocyanates occurs in a continuously operating mixing assembly.

15. The use according to any of claims 11 to 14, wherein the reaction time of the thermofused polyurethane prepolymer with the polyisocyanate or polyisocyanates before shaping does not exceed 10 minutes, and more particularly is within a time window of 2 seconds to 5 minutes.